19-3382; Rev 1; 10/04 Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection The MAX7500/MAX7501/MAX7502 temperature sensors accurately measure temperature and provide an over-temperature alarm/interrupt/shutdown output. These devices convert the temperature measurements to digital form using a high-resolution, sigma-delta, analog-to-digital converter (ADC). Communication is through an I2C-compatible 2-wire serial interface. The MAX7500/MAX7501/MAX7502 integrate a timeout feature that offers protection against I2C bus lockups. The 2-wire serial interface accepts standard write byte, read byte, send byte, and receive byte commands to read the temperature data and configure the behavior of the open-drain over-temperature shutdown output. The MAX7500 features three address select lines, while the MAX7501 and MAX7502 feature two address select lines and a RESET input. The MAX7500/MAX7501/ MAX7502s’ 3.0V to 5.5V supply voltage range, low 250µA supply current, and a lockup-protected I 2Ccompatible interface make them ideal for a wide range of applications, including personal computers (PCs), electronic test equipment, and office electronics. The MAX7500/MAX7501/MAX7502 are available in 8pin µMAX® and SO packages and operate over the -55°C to +125°C temperature range. Applications PCs Servers Office Electronics Electronic Test Equipment Industrial Process Control Features ♦ ♦ ♦ ♦ Timeout Prevents Bus Lockup I2C Bus Interface 3.0V to 5.5V Supply Voltage Range 250µA (typ) Operating Supply Current ♦ 3µA (typ) Shutdown Supply Current ♦ ±2°C (max) from -25°C to +100°C Temperature Accuracy ♦ µMAX, SO Packages Save Space ♦ Separate Open-Drain OS Output Operates as Interrupt or Comparator/Thermostat Input ♦ Register Readback Capability ♦ Improved LM75 Second Source Ordering Information PART TEMP RANGE PIN-PACKAGE -55°C to +125°C 8 SO MAX7500MUA -55°C to +125°C 8 µMAX MAX7501MSA -55°C to +125°C 8 SO MAX7501MUA -55°C to +125°C 8 µMAX MAX7502MSA -55°C to +125°C 8 SO MAX7502MUA -55°C to +125°C MAX7500MSA 8 µMAX I2C is a trademark of Philips Corp. Purchase of I2C components from Maxim Integrated Products Inc., or one of its sublicensed Associated Companies, conveys a license under Philips I2C Patent Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification as defined by Philips. µMAX is a registered trademark of Maxim Integrated Products, Inc. Pin Configurations TOP VIEW SDA 1 8 +VS SDA 1 8 SCL 2 7 A0 SCL 2 7 A0 OS 3 6 A1 OS 3 6 A1 GND 4 5 A2 GND 4 5 RESET MAX7500 µMAX, SO MAX7501 MAX7502 +VS µMAX, SO ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX7500/MAX7501/MAX7502 General Description MAX7500/MAX7501/MAX7502 Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection ABSOLUTE MAXIMUM RATINGS Continuous Power Dissipation (TA = +70°C) 8-Pin µMAX (derate 4.5mW/°C above +70°C) ............ 362mW 8-Pin SO (derate 5.9mW/°C above +70°C)................. 471mW Operating Temperature Range ....................... -55°C to +125°C Junction Temperature .................................................... +150°C Storage Temperature Range ........................... -65°C to +150°C Lead Temperature (soldering, 10s) ............................... +300°C (Note 1) +VS to GND ............................................................. -0.3V to +6V OS, SDA, SCL to GND.......................................... -0.3V to +6.0V All Other Pins to GND ................................ -0.3V to (+VS + 0.3V) Input Current at Any Pin (Note 2) ..................................... +5mA Package Input Current (Note 2) ..................................... +20mA ESD Protection (all pins, Human Body Model, Note 3)... ±2000V Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating the device beyond its rated operating conditions. Note 2: When the input voltage (VI) at any pin exceeds the power supplies (VI < GND or VI > + VS), the current at that pin should be limited to 5mA. The 20mA maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5mA to 4. Note 3: Human Body Model, 100pF discharged through a 1.5kΩ resistor. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (+VS = +3.0V to +5.5V, TA = -55°C to +125°C, unless otherwise noted. Typical values are at +VS = +3.3V, TA = +25°C.) (Notes 4, 5) PARAMETER SYMBOL Accuracy CONDITIONS MIN -55°C ≤ TA ≤ +125°C ±3.0 (Note 6) 2 I C inactive Quiescent Supply Current MAX ±2.0 Resolution Conversion Time TYP -25°C ≤ TA ≤ +100°C 9 Bits ms 0.25 3 Shutdown mode, +VS = 5V 5 3.0 OS Output Saturation Voltage IOUT = 4.0mA (Note 7) OS Delay (Note 8) °C 100 Shutdown mode, +VS = 3V +VS Supply Voltage Range UNITS 1 0.5 mA µA 5.5 V 0.8 V 6 Conversions TOS Default Temperature (Note 9) 80 °C THYST Default Temperature (Note 9) 75 °C LOGIC (SDA, SCL, A0, A1, A2) +VS x 0.7 Input High Voltage VIH Input Low Voltage VIL Input High Current IIH VIN = 5V Input Low Current IIL VIN = 0V Input Capacitance All digital inputs Output High Current VIN = 5V Output Low Voltage IOL = 3mA 2 V 0.005 +VS x 0.3 1.0 µA 0.005 1.0 µA 1 µA 0.4 V 5 _______________________________________________________________________________________ V pF Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection (+VS = +3.0V to +5.5V, TA = -55°C to +125°C, unless otherwise noted. Typical values are at +VS = +5V, TA = +25°C.) (Notes 4, 5) PARAMETER SYMBOL I2C-COMPATIBLE TIMING (Note 10) Serial Clock Frequency fSCL Minimum RESET Pulse Width Bus Free Time Between STOP and START Conditions START Condition Hold Time tHD:STA STOP Condition Setup Time tSU:STO CONDITIONS Bus timeout inactive tBUF 90% of SCL to 10% of SDA MIN TYP DC MAX UNITS 400 kHz 1 µs 1.3 µs 0.6 µs 100 ns Clock Low Period tLOW 1.3 µs Clock High Period tHIGH 0.6 µs ns START Condition Setup Time tSU:STA 90% of SCL to 90% of SDA 100 Data Setup Time tSU:DAT 10% of SDA to 10% of SCL 100 Data Hold Time tHD:DAT 10% of SCL to 10% of SDA (Note 11) Maximum Receive SCL/SDA Rise Time tR Minimum Receive SCL/SDA Rise Time tR Maximum Receive SCL/SDA Fall Time tF Minimum Receive SCL/SDA Fall Time tF (Note 12) Transmit SDA Fall Time tF (Note 12) Pulse Width of Suppressed Spike tSP (Note 13) 20 + 0.1 x CB 0 SDA Time Low for Reset of Serial Interface tTIMEOUT (Note 14) 150 Note 4: Note 5: Note 6: Note 7: Note 8: Note 9: Note 10: Note 11: Note 12: Note 13: Note 14: ns 0 (Note 12) 0.9 µs 300 ns 20 + 0.1 x CB ns 300 ns 20 + 0.1 x CB ns 250 ns 50 ns 300 ms All parts operate properly over the +VS = 3V to 5V supply voltage range. The devices are tested and specified for rated accuracy at their nominal supply voltage. Accuracy typically degrades 1°C per volt of change in +VS as it varies from the nominal value. All parameters are measured at +25°C. Values over the temperature range are guaranteed by design. This specification indicates how often temperature data is updated. The devices can be read at any time without regard to conversion state, while yielding the last conversion result. For best accuracy, minimize output loading. Higher sink currents can affect sensor accuracy due to internal heating. OS delay is user programmable up to six “over-limit” conversions before OS is set to minimize false tripping in noisy environments. Default values set at power-up. All timing specifications are guaranteed by design. A master device must provide a hold time of at least 300ns for the SDA signal to bridge the undefined region of SCL’s falling edge. CB = total capacitance of one bus line in pF. Tested with CB = 400pF. Input filters on SDA, SCL, and A_ suppress noise spikes less than 50ns. Holding the SDA line low for a time greater than tTIMEOUT causes the devices to reset SDA to the IDLE state of the serial bus communication (SDA set high). _______________________________________________________________________________________ 3 MAX7500/MAX7501/MAX7502 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE +VS = +5V 270 260 +VS = +3V 250 240 230 5 1.0 +VS = +5V 4 3 +VS = +3V 2 -25 5 35 65 125 95 0.5 0 -0.5 -1.0 1 -1.5 -2.0 0 -55 4 TYPICAL PARTS 1.5 ACCURACY (°C) 280 ACCURACY vs. TEMPERATURE 2.0 MAX7500 toc02 290 6 SHUTDOWN SUPPLY CURRENT (µA) MAX7500 toc01 300 MAX7500 toc03 QUIESCENT SUPPLY CURRENT vs. TEMPERATURE QUIESCENT SUPPLY CURRENT (µA) MAX7500/MAX7501/MAX7502 Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection -55 TEMPERATURE (°C) -25 5 35 65 95 125 -55 -25 5 35 65 95 125 TEMPERATURE (°C) TEMPERATURE (°C) Pin Description PIN NAME 1 MAX7501 MAX7502 1 2 2 SCL Serial Data Clock Input. Open drain. Connect SCL to a pullup resistor. 3 3 OS Over-Temperature Shutdown Output. Open drain. Connect OS to a pullup resistor. 4 4 GND 5 — A2 2-Wire Interface Address Input. Connect A2 to GND or +VS to set the desired I2C bus address. Do not leave floating. (See Table 1.) — 5 RESET Active-Low Reset Input. Pull RESET low for longer than the minimum reset pulse width to reset the I2C bus and all internal registers to their POR values. 6 6 A1 2-Wire Interface Address Input. Connect A1 to GND or +VS to set the desired I2C bus address. Do not leave floating. (See Table 1.) 7 7 A0 2-Wire Interface Address Input. Connect A0 to GND or +VS to set the desired I2C bus address. Do not leave floating. (See Table 1.) 8 8 +VS Positive Supply Voltage Input. Bypass to GND with a 0.1µF bypass capacitor. MAX7500 SDA FUNCTION Serial Data Input/Output Line. Open drain. Connect SDA to a pullup resistor. Ground Detailed Description The MAX7500/MAX7501/MAX7502 temperature sensors measure temperature, convert the data into digital form using a sigma-delta ADC, and communicate the conversion results through an I2C-compatible 2-wire serial interface. These devices accept standard I 2C commands to read the data, set the over-temperature 4 alarm (OS) trip thresholds, and configure other characteristics. The MAX7500 features three address select lines (A0, A1, A2) while the MAX7501 and MAX7502 feature two address select lines (A0, A1) and a RESET input. The MAX7500/MAX7501/MAX7502 operate from +3.0V to +5.5V supply voltages of and consume 250µA of supply current. _______________________________________________________________________________________ Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection MAX7500/MAX7501/MAX7502 Table 1. I2C Slave Addresses DEVICE BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 MAX7500 1 0 0 1 A2 A1 A0 RD/W MAX7501 1 0 0 1 1 A1 A0 RD/W MAX7502 1 0 0 1 0 A1 A0 RD/W SDA tBUF tSU:DAT tSU:STA tSU:STO tHD:DAT tLOW tHD:STA SCL tHIGH tHD:STA tR tF START CONDITION (S) REPEATED START CONDITION (SR) ACKNOWLEDGE (A) STOP CONDITION (P) START CONDITION (S) PARAMETERS ARE MEASURED FROM 10% TO 90%. Figure 1. Serial Bus Timing I2C-Compatible Bus Interface From a software perspective, the MAX7500/MAX7501/ MAX7502 appear as a set of byte-wide registers that contain temperature data, alarm threshold values, and control bits. A standard I2C-compatible 2-wire serial interface reads temperature data and writes control bits and alarm threshold data. Each device responds to its own I2C slave address, which is selected using A0, A1, and A2. See Table 1. The MAX7500/MAX7501/MAX7502 employ four standard I2C protocols: write byte, read byte, send byte, and receive byte (Figures 1, 2, and 3). The shorter receive byte protocol allows quicker transfers, provided that the correct data register was previously selected by a read-byte instruction. Use caution when using the shorter protocols in multimaster systems, as a second master could overwrite the command byte without informing the first master. The MAX7500 has eight different slave addresses available; therefore, a maximum of eight MAX7500 devices can share the same bus. The MAX7501/MAX7502 each have four different slave addresses available. _______________________________________________________________________________________ 5 6 START BY MASTER START BY MASTER START BY MASTER ADDRESS BYTE ADDRESS BYTE ADDRESS BYTE POINTER BYTE ACK BY MAX7500/ MAX7501/ MAX7502 REPEAT START BY MASTER ADDRESS BYTE ACK BY MAX7500/ MAX7501/ MAX7502 ACK BY MAX7500/ MAX7501/ MAX7502 ACK BY MAX7500/ MAX7501/ MAX7502 POINTER BYTE POINTER BYTE MOST-SIGNIFICANT DATA BYTE (c) THIGH AND TLOW WRITE ACK BY MAX7500/ MAX7501/ MAX7502 ACK BY CONFIGURATION MAX7500/ BYTE MAX7501/ MAX7502 (b) CONFIGURATION REGISTER WRITE ACK BY MAX7500/ MAX7501/ MAX7502 DATA BYTE LEAST-SIGNIFICANT DATA BYTE STOP COND BY ACK BY MASTER MAX7500/ MAX7501/ MAX7502 (a) TYPICAL POINTER SET FOLLOWED BY IMMEDIATE READ FROM CONFIGURATION REGISTER ACK BY MAX7500/ MAX7501/ MAX7502 ACK BY MAX7500/ MAX7501/ MAX7502 STOP COND BY MASTER NO ACK BY MASTER STOP COND BY MASTER MAX7500/MAX7501/MAX7502 Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection Figure 2. I2C-Compatible Timing Diagram (Write) _______________________________________________________________________________________ _______________________________________________________________________________________ START BY MASTER START BY MASTER START BY MASTER REPEAT START BY MASTER ADDRESS BYTE ADDRESS BYTE ADDRESS BYTE ACK BY MASTER ACK BY MASTER LEAST-SIGNIFICANT DATA BYTE ACK BY MAX7500/ MAX7501/ MAX7502 POINTER BYTE MOST-SIGNIFICANT DATA BYTE ACK BY MAX7500/ MAX7501/ MAX7502 ACK BY MASTER DATA BYTE NO ACK BY MASTER (c) TYPICAL 1-BYTE READ FROM CONFIGURATION REGISTER WITH PRESET POINTER. ACK BY MAX7500/ MAX7501/ MAX7502 STOP COND BY MASTER (b) TYPICAL POINTER SET FOLLOWED BY IMMEDIATE READ FOR 2-BYTE REGISTER SUCH AS TEMP, THIGH, TLOW. ADDRESS BYTE MOST-SIGNIFICANT DATA BYTE (a) TYPICAL 2-BYTE READ FROM PRESET POINTER LOCATION SUCH AS TEMP, THIGH, TLOW. ACK BY MAX7500/ MAX7501/ MAX7502 LEAST-SIGNIFICANT DATA BYTE NO ACK BY MASTER NO ACK BY MASTER STOP COND BY MASTER MAX7500/MAX7501/MAX7502 STOP COND BY MASTER Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection Figure 3. I2C-Compatible Timing Diagram (Read) 7 MAX7500/MAX7501/MAX7502 Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection Table 2. Register Functions REGISTER NAME ADDRESS (hex) POR STATE (hex) POR STATE (BINARY) POR STATE (°C) READ/ WRITE Temperature 00 — — — Read only Configuration 01 00 0000 0000 — R/W THYST 02 4B0 0100 1011 0 75 R/W TOS 03 500 0101 0000 0 80 R/W Table 3. Temperature Register Definition UPPER BYTE LOWER BYTE D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Sign bit 1= Negative 0 = Positive MSB 64°C 32°C 16°C 8°C 4°C 2°C 1°C LSB 0.5°C x x x x x x x X = Don’t care. Register Descriptions The MAX7500/MAX7501/MAX7502 have an internal pnjunction-based temperature sensor whose analog output is converted to digital form using a 9-bit sigma-delta ADC. The measured temperature and temperature configurations are controlled by the temperature, configuration, T HYST , and T OS registers. See Table 2. Temperature Register Read the measured temperature through the temperature register. The temperature data format is 9 bits, two’s complement, and the register is read out in 2 bytes: an upper byte and a lower byte. Bit D15 is the sign bit. When bit D15 is 1, the temperature reading is negative. When bit D15 is zero, the temperature reading is positive. Bits D14–D7 contain the temperature data, with the LSB representing 0.5°C and the MSB representing 64°C (see Table 3). The MSB is transmit- Table 4. Temperature Data Output TEMPERATURE (°C) +125 8 DIGITAL OUTPUT BINARY hex 0111 1101 0xxx xxxx 7D0x +25 0001 1001 0xxx xxxx 190x +0.5 0000 0000 1xxx xxxx 008x 0 0000 0000 0xxx xxxx 000x -0.5 1111 1111 1xxx xxxx FF8x -25 1110 0110 0xxx xxxx E70x -55 1100 1000 0xxx xxxx C90x ted first. The last 7 bits of the lower byte, bits D6–D0, are don’t cares. When reading the temperature register, bits D6–D0 must be ignored. When the measured temperature is greater than +127.5°C, the value stored in the temperature register is clipped to 7F8h. When the measured temperature is below -64°C, the value in the temperature register is clipped to BF8h. During the time of reading the temperature register, any changes in temperature are ignored until the read is completed. The temperature register is updated upon completion of the next conversion. Table 3 lists the temperature register definition. Configuration Register The 8-bit configuration register sets the fault queue, OS polarity, shutdown control, and whether the OS output functions in comparator or interrupt mode. When writing to the configuration register, set bits D7, D6, and D5 to zero. See Table 5. Bits D4 and D3, the fault queue bits, determine the number of faults necessary to trigger an OS condition. See Table 6. The number of faults set in the queue must occur to trip the OS output. The fault queue prevents OS false tripping in noisy environments. Set bit D2, the OS polarity bit, to zero to force the OS output active low. Set bit D2 to 1 to set the OS output polarity to active high. OS is an open-drain output under all conditions and requires a pullup resistor to output a high voltage. See Figure 4. Set bit D1, the comparator/interrupt bit to zero to run the over-temperature shutdown block in comparator mode. In comparator mode, OS is asserted when the _______________________________________________________________________________________ Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection D7 D6 0 D5 0 D4 0 D3 Fault queue Fault queue Table 6. Configuration Register Fault Queue Bits D4 D3 NO. OF FAULTS 0 0 1 (POR state) 0 1 2 1 0 4 1 1 6 D2 D1 D0 OS polarity Comparator/ interrupt Shutdown TOS TEMPERATURE THYST OS OUTPUT (COMPARATOR MODE) OS SET ACTIVE LOW temperature rises above the TOS value. OS is deasserted when the temperature drops below the THYST value. See Figure 4. Set bit D1 to 1 to run the over-temperature shutdown block in interrupt mode. OS is asserted in interrupt mode when the temperature rises above the T OS value or falls below the T HYST value. OS is deasserted only after performing a read operation. Set bit D0, the shutdown bit, to zero for normal operation. Set bit D0 to 1 to shut down the MAX7500/ MAX7501/MAX7502 internal blocks, dropping the supply current to 3µA. The I2C interface remains active as long as the shutdown bit is set. The TOS, THYST, and configuration registers can still be written to and read from while in shutdown. OS OUTPUT (INTERRUPT MODE) OS SET ACTIVE LOW READ OPERATION READ OPERATION READ OPERATION Figure 4. OS Timing Diagram In interrupt mode, exceeding TOS also asserts OS. OS remains asserted until a read operation is performed on any of the registers. Once OS has asserted due to crossing above TOS and is then reset, it is asserted again only when the temperature drops below THYST. The output remains asserted until it is reset by a read. Putting the MAX7500/MAX7501/MAX7502 into shutdown mode also resets OS. TOS and THYST Registers In comparator mode, the OS output behaves like a thermostat. The output asserts when the temperature rises above the limit set in the T OS register. The output deasserts when the temperature falls below the limit set in the THYST register. In comparator mode, the OS output can be used to turn on a cooling fan, initiate an emergency shutdown signal, or reduce system clock speed. The T OS and T HYST registers are accessed with 2 bytes, with bits D15–D7 containing the data. Bits D6–D0 are don’t cares when writing to these two registers and read-back zeros when reading from these registers. The LSB represents 0.5°C while the MSB represents 64°C. See Table 7. Table 7. TOS and THYST Register Definitions UPPER BYTE COMMAND LOWER BYTE D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Write Sign bit 1 = negative 0 = positive MSB 64°C 32°C 16°C 8°C 4°C 2°C 1°C LSB 0.5°C x x x x x x x Read Sign bit 1 = negative 0 = positive MSB 64°C 32°C 16°C 8°C 4°C 2°C 1°C LSB 0.5°C 0 0 0 0 0 0 0 X = Don’t care. _______________________________________________________________________________________ 9 MAX7500/MAX7501/MAX7502 Table 5. Configuration Register Definition MAX7500/MAX7501/MAX7502 Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection Shutdown +VS Set bit D0 in the configuration register to 1 to place the MAX7500/MAX7501/MAX7502 in shutdown mode and reduce supply current to 3µA. Power-Up and Power-Down The MAX7500/MAX7501/MAX7502 power up to a known state, as indicated in Table 2. Some of these settings are summarized below: • Comparator mode • TOS = +80°C • THYST = +75°C • OS active low • Pointer = 00 Internal Registers The MAX7500/MAX7501/MAX7502s’ pointer register selects between four data registers. See Figure 5. At power-up, the pointer is set to read the temperature register at address 00. The pointer register latches the last location to which it was set. All registers are read and write, except the temperature register, which is read only. Write to the configuration register by writing an address byte, a data pointer byte, and a data byte. If 2 data bytes are written, the second data byte overrides the first. If more than 2 data bytes are written, only the first 2 bytes are recognized while the remaining bytes are ignored. The T OS and T HYST registers require 1 address byte and 1 pointer byte and 2 data bytes. If only 1 data byte is written, it is saved in bits D15–D8 of the respective register. If more than 2 data bytes are written, only the first 2 bytes are recognized while the remaining bytes are ignored. Read from the MAX7500/MAX7501/MAX7502 in one of two ways. If the location latched in the pointer register is set from the previous read, the new read consists of an address byte, followed by retrieving the corresponding number of data bytes. If the pointer register needs to be set to a new address, perform a read operation by writing an address byte, pointer byte, repeat start, and another address byte. An inadvertent 8-bit read from a 16-bit register, with the D7 bit low, can cause the MAX7500/MAX7501/ MAX7502 to stop in a state where the SDA line is held low. Ordinarily, this would prevent any further bus communication until the master sends nine additional clock cycles or SDA goes high. At that time, a stop condition 10 A0 A1 A2/RESET SDA SMBus INTERFACE BLOCK SCL DATA MAX7500 MAX7501 MAX7502 OS ADDRESS POINTER REGISTER (SELECTS REGISTER FOR COMMUNICATION) REGISTER SELECT TEMPERATURE (READ ONLY) POINTER = 0000 0000 CONFIGURATION (READ/WRITE) POINTER = 0000 0001 TOS SET POINT (READ/WRITE) POINTER = 0000 0011 THYST SET POINT (READ/WRITE) POINTER = 0000 0010 GND Figure 5. Block Diagram resets the device. With the MAX7500/MAX7501/ MAX7502, if the additional clock cycles are not generated by the master, the bus resets and unlocks after the bus timeout period has elapsed. The MAX7501/MAX7502 can be reset by pulsing RESET low. Bus Timeout Communication errors sometimes occur due to noise pickup on the bus. In the worst case, such errors can cause the slave device to hold the data line low, thereby preventing other devices from communicating over the bus. The MAX7500/MAX7501/MAX7502s’ internal bus timeout circuit resets the bus and releases the data line if the line is low for more than 250ms. When the bus timeout is active, the minimum serial clock frequency is limited to 6Hz. RESET The RESET input on the MAX7501/MAX7502 provides a way to reset the I2C bus and all the internal registers to their initial POR values. To reset, apply a low pulse with a duration of at least 1µs to the RESET input. ______________________________________________________________________________________ Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection Digital Noise The MAX7500/MAX7501/MAX7502 feature an integrated lowpass filter on both the SCL and the SDA digital lines to mitigate the effects of bus noise. Although this filtering makes communication robust in noisy environments, good layout practices are always recommended. Minimize noise coupling by keeping digital traces away from switching power supplies. Ensure that digital lines containing high-speed data communications cross at right angles to the SDA and SCL lines. Excessive noise coupling into the SDA and SCL lines on the MAX7500/MAX7501/MAX7502—specifically noise with amplitude greater than 400mV P-P (the MAX7500/MAX7501/MAX7502s’ typical hysteresis), overshoot greater than 300mV above +VS , and undershoot more than 300mV below GND—may prevent suc- cessful serial communication. Serial bus no-acknowledge is the most common symptom, causing unnecessary traffic on the bus. Care must be taken to ensure proper termination within a system with long PC board traces or multiple parts on the bus. Resistance can be added in series with the SDA and SCL lines to further help filter noise and ringing. If it proves to be necessary, a 5kΩ resistor should be placed in series with the SCL line, placed as close as possible to SCL. This 5kΩ resistor, with the 5pF to 10pF stray capacitance of the MAX7500/MAX7501/ MAX7502 provide a 6MHz to 12MHz lowpass filter, which is sufficient filtering in most cases. Chip Information TRANSISTOR COUNT: 9611 PROCESS: CMOS ______________________________________________________________________________________ 11 MAX7500/MAX7501/MAX7502 Applications Information Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) 4X S 8 E 0.50–0.1 8 INCHES DIM A A1 A2 b H c D e E H 0.6–0.1 1 L 1 α 0.6–0.1 S BOTTOM VIEW D MIN 0.002 0.030 MAX 0.043 0.006 0.037 0.014 0.010 0.007 0.005 0.120 0.116 0.0256 BSC 0.120 0.116 0.198 0.188 0.026 0.016 6 0 0.0207 BSC 8LUMAXD.EPS MAX7500/MAX7501/MAX7502 Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection MILLIMETERS MAX MIN 0.05 0.75 1.10 0.15 0.95 0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0 6 0.5250 BSC TOP VIEW A1 A2 A α c e FRONT VIEW b L SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 8L uMAX/uSOP APPROVAL DOCUMENT CONTROL NO. 21-0036 12 ______________________________________________________________________________________ REV. J 1 1 Digital Temperature Sensors and Thermal Watchdog with Bus Lockup Protection N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS DIM A A1 B C e E H L 1.27 VARIATIONS: 1 INCHES TOP VIEW DIM D D D MIN 0.189 0.337 0.386 MAX 0.197 0.344 0.394 MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC D C A B e 0 -8 A1 L FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, .150" SOIC APPROVAL DOCUMENT CONTROL NO. 21-0041 REV. B 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13 © 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX7500/MAX7501/MAX7502 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)